Interpretive Summary: Harmomic radar offers a novel method for tracking small, cryptic insects under natural conditions. However, this approach requires that a small tag be attached to the insect body in order to detect the insect. The presence of this tag may impede the insect as it moves through the environment. In order to determine the level of nuisance or entanglement created by the presence of the tag, we tracked adult Colorado potato beetles, plum curculios, and western corn rootworms with and without different types of tags in field plots and under laboratory conditions. We found that the insects were largely unaffected by the presence of vertical tags and could walk on the ground, demonstrating viable horizontal movement and also walk up vertical surfaces successfully. Harmonic radar appears to be a viable approach for tracking insect movement under natural field conditions and developing a better understanding of how pest species colonize their host plants.

Technical Abstract:
The observation of insects and other small organisms entangled in the habitat after the addition of vertical or trailing electronic tags to their body has generated concerns on the suitability of harmonic radars to track the dispersal of insects. This study compared the walking behavior of adult Colorado potato beetles, plum curculios, and western corn rootworms with and without vertical and or trailing tags in field plots or arenas. The frequency of insects crossing bare ground or grassy plots was unaffected by the presence of vertical harmonic radar tags. However, the smaller size plum curculios and western corn rootworms were either unable to walk with a 4 cm trailing tag (plum curculio) or displayed a reduced ability to successfully cross a bare ground arena. The frequency of the larger Colorado potato beetles crossing bare ground or grassy plots was unaffected by the presence of 8 cm trailing harmonic radar tags. Our results revealed the significant impact of vegetation on successful insect dispersal, whether tagged or not. The vertical movement of these insects on stems, stalks, and tubes was also unaffected by the presence of vertical tags, but trailing tags had a significant negative effect on the vertical movement of the western corn rootworm. Results show that harmonic radar technology is a sound method for studying the walking paths of insects with appropriate tag type and size. The nuisance factor generated by the tag was small compared to that of vegetation and what we learn from the study.